Measurements of the backscattering characteristics of suspensions having a broad particle size distribution

Acoustic backscatter systems (ABS) can be used to non-intrusively measure profiles of both the concentration and particle size of suspended sediments in the marine environment. Inversion of ABS measurements into sediment size and concentration requires knowledge of two scattering parameters, namely the total normalised scattering cross-section, &chi;, and the form function, f. &chi; quantifies the acoustical scattering by a given particle over all angles, relative to its cross sectional area, and represents attenuation due to particle scattering losses. f describes the backscattering characteristics of a particle relative to its geometrical size. In recent years, a number of studies have presented measurements of f and &chi; for populations of sediments sieved over narrow size ranges, thereby essentially providing values for nominally a single particle size in suspension. In the present study, we extend these works by looking at the impact that a broad particle size distribution has on the form of f and &chi;. Here we model and measure the average form function for a broad size distribution (&sigma; = ±0.35a0, where &sigma; is the standard deviation about the mean particle radius, a0) of suspended glass spheres, whose scattering characteristics are well documented. The model is in close agreement with the provisional measurements, and suggests that for populations of suspended glass spheres with broad size distributions, the form function increases by about 40% in the Rayleigh regime (&lambda; >> 2&pi;a0, where &lambda; is the wavelength of the sound in water), whilst decreasing by a factor of around 25% in the geometric regime (&lambda; << 2&pi;a0), relative to that obtained for populations with a nominally single size in suspension. The output from this work has direct implications for the calculation of particle size and concentration profiles, obtained from acoustic backscatter data collected on suspensions of marine sediments at sea

Measurements of the scattering characteristics of sediment suspensions with different mineralogical compositions

Acoustic studies of suspended sediments often assume the dominant mineral in suspension is quartz, the density and intrinsic scattering properties of which are implemented when inverting acoustic backscatter data collected at sea. However, compositional analysis studies of suspended and sea-bed particulate material show a wide range of mineral species contribute to the inorganic fraction of sediments in the marine environment. Whilst no theoretical framework exists to predict the acoustic properties of irregularly shaped sediment grains, the density, compressional, and shear wave velocities of common marine mineral species can vary by up to a factor of two. In this study, we present and compare measurements of the intrinsic scattering parameters, namely the normalized total scattering cross section, χ, and the backscatter form function, f, obtained from homogenous suspensions of irregularly shaped sand sized grains of both magnetite and quartz. Our preliminary measurements suggest that in the geometric scattering regime, χ is enhanced for magnetite sands by ~ 100 % relative to quartz. Similarly, measurements of the form function for magnetite sands are enhanced by ~ 33 % relative to quartz in the geometric regime, though no measurable difference was observed in the Rayleigh regime. The implications of these results for acoustic backscatter data collected at sea are discussed

Conceptualising Female Perpetrated Violence Towards Intimate Male Partners: A Delphi Study of Expert’s Views

Despite increased acknowledgement that males as well as females can be victims of intimate partner violence, compared to the extensive literature on male perpetrators of intimate partner abuse, the literature on female perpetrated violence towards male partners is exceptionally scarce (Dutton, Nicholls & Spidel, 2005). What is evident from the research that does exist, is that there is a lack of discussion and consensus in regards to the causal explanations specific to this type of female violence. The present study aimed to address this by exploring the ways in which local experts in the field of family and domestic violence conceptualise female perpetrated violence towards intimate male partners. Participants (N = 10) were drawn from a variety of sectors within the field of family and domestic violence including women’s refuges, police, policy, community-based services and the legal system. A two round interview and analysis process was adopted, with the initial interview identifying the participant’s positions in relation to the research questions, and the second encouraging the experts to revise their opinions in light of the other participant’s responses, in order to bring them closer to consensus. The data was analysed using thematic analysis and suggests current theories of domestic violence do not comprehensively explain female perpetrated violence towards intimate male partners. Further research establishing frameworks that can better explain female perpetrated intimate partner violence is necessary if effective services for both male victims and female perpetrators of domestic violence are to be constructed

Investigating the Potential Effects of Pollutants on the Rainbow Trout (Oncorhynchus mykiss) Gastrointestinal Microbiome

The gastrointestinal (GI) microbiome is an important aspect of organismal health with the ability to affect host nutrition, metabolic processes, and immune system development. Changes to the GI microbiome can affect any of these or other host functions and could result in negative effects on overall fish health. While it is known that low concentrations of pollutants can affect environmental microbes, little information is known about the effects of environmental contaminants on GI microbiota in fish. I conducted two studies to explore the potential effects of chemicals on the GI microbiome of fish. The pilot study aimed to develop a method to extract and analyse the microbiota within the GI tract of fish. It also compared the microbiomes of two phylogenetically distant fish species, lake sturgeon (Acipenser fulvescens) and rainbow trout (Oncorhynchus mykiss), under controlled conditions. The second study aimed to discover the effects of two common environmental contaminants, benzo(a)pyrene (BaP) and triclosan, on the GI microbiome in rainbow trout. In both experiments, DNA was extracted from intestinal contents of fish and GI microbiota were evaluated using next-generation sequencing techniques and downstream applications. The pilot study suggested GI microbial communities were more diverse in rainbow trout and were significantly different from those communities in lake sturgeon. Due to the similarities in rearing conditions and diet in the laboratory, microbial differences between the two species may indicate evolutionary differences. In the second study, the GI microbiomes of rainbow trout were compared after exposure to four different diets (solvent control, 5.09 mg/kg BaP, 40.7 mg/kg BaP and a mixture of 4.58 mg/kg BaP + 2.89 mg/kg triclosan) and sampled at each of three time points (exposure: one and 21 days; recovery: 28 days). Proteobacteria was dominant across all treatments and at all time points. Firmicutes, Tenericutes or Fusobacteria was the next most dominant phylum, depending on treatment and/or time. There were significant differences in both treatment and time. Composition was significantly different among treatment groups during each individual time, and time points differed for all treatments except the solvent control. Differences over time may be due to initial introduction of contaminants, followed by coping mechanisms, and recovery when exposure was removed. Together, these results suggest that fish species, chemical exposure, and duration of exposure all contribute to differences in the GI microbial composition of fish. Thus, the complexity of this system needs to be considered when identifying potential biomarkers of pollutant exposure in wild fish

OFFSHORE FOULING COMMUNITIES AND SETTLEMENT AND EARLY GROWTH IN Tubularia larynx (ELLIS AND SOLANDER) AND Pomatoceros triqueter (L.)

Merged with duplicate record 10026.1/663 on 28.02.2017 by CS (TIS)The horizontal and vertical distribution of the macro-fouling organisms, both flora and fauna, associated with offshore structures was studied. Offshore buoys located around the coasts of Britain (38) and Norway (10), were used as sites for the collection of material. Sites were visited annually, when possible, over the period 1978-1983. Numerical clustering techniques and indicator species analysis were used to reveal broad geographical categories in the fouling community data. Eight major Site Groups were identified amongst U.K. sites, and three from Norway; whilst within each site group characteristic species were also identified. The frequency and abundance of Tubularia larynx and Pomatoceros triqueter at both the British and Norwegian sites indicated that each species was a 'successful' member of the fouling communities examined, and able to rapidly colonize newly immersed hard substrata. Light microscopy, histochemical techniques and electron microscopy were used to investigate the mechanisms of substrate attachment and settlement in both species. It is postulated that the secretion of an acidic 'adhesive' mucosubstance prior to the secretion of the calcareous tube in Pomatoceros may contribute to the successful colonization of hard surfaces; whilst a rapid chitin tanning process was identified during 'growth' of the aboral pole of the settling actinula larva in Tubularia, as well as in the subsequent vegetative growth of 'primary' stolen tips. In addition, a gregarious settlement-response was identified in Pomatoceros larvae. Several growth experiments were performed on each animal and a multifactorial approach was used to investigate the conditions for early growth in each organism. Both species were capable of rapid growth immediately following settlement. 'Tubegrowth' was recorded in Pomatoceros under a wide range of temperature and salinity conditions; being greatest amongst animals maintained in combinations of high temperature (15-200C) and high salinity (26-34‰), whilst the secretion of new tube was much reduced at 60C and 10‰. In Tubularia, although growth was rapid between 60C and 18°C., the hydroid was more strictly marine and both stolonic growth and hydranth production were restricted in salinities below 28‰.THE ADMIRALTY MARINE TECHNOLOGY ESTABLISHMENT PORTSMOUT

Acoustic measurements of boundary layer flux profiles over a sandy rippled bed under regular waves

The study of boundary layer sediment transport processes requires contemporaneous measurements of the bedforms, the flow and the sediment movement. Obtaining these three parameters, at the required temporal-spatial resolutions, has been traditionally difficult, especially within a few centimetres of the bed. To circumvent some of the deployment of an acoustic backscatter system, ABS, an acoustic ripple profiler, ARP, and an acoustic Doppler velocity profiler, ADVP, to measure sediment entrainment processes above a rippled bed under regular waves. High resolution acoustic observations of the suspend sediment concentration, flow and bedforms have been collected. Here we report on some of the initial results obtained from this study

Qui suis-je : Discontinuity as part of teacher identity in Canadian French immersion

The scarcity of research on French immersion teachers’ professional identity contrasts with the increasing popularity of French immersion programs in Canada and the concomitant need for French immersion teachers. This study explores the professional identity negotiation of four French immersion teachers in Alberta, Canada, with a focus on discontinuity. Semi-structured interviews conducted face-to-face with the participants were analysed using dialogic narrative analysis. The findings highlight how discontinuity is occasioned by a change in knowledge about the French immersion teaching as a profession, encountering classroom realities, shifting one’s values concerning second language learning and the emotions one experiences in moments of discontinuity. A negative change in emotion may encourage discontinuity in immersion teacher identity and teachers’ understanding of themselves as second language learners. On the other hand, positive emotions underline the harboured passion for French and second language learning and may help re-align French immersion teacher identity to the sense of purpose teachers identified in their professional lives. The study concludes with a discussion of certain considerations arising from the data.Peer reviewe

Dialogic Space and Religious Education

This review hopes to present an alternative model to confessional religious education and the kind of role religion can have in teaching and education. It is framed by the conceptualization of education as simultaneously being and becoming (van Manen 1991, 67). This dichotomous description underlines the challenging tension of balancing present realities with future anticipations, a tension which is perhaps the defining feature of education. In theoretical terms this review draws on sociocultural and dialogic educational research, particularly Rupert Wegerif’s notion of “dialogic space” (Wegerif 2007, 4), and a “Global Education: World Religions” -course recently run as part of the Summer School for Human Sciences at the University of Jyväskylä. The review opens by introducing the pedagogic orientation for the course and a simple cultural model developed within the course. Following this, the guidelines for the development of “dialogic space” are introduced with possible implications for Religious Education concluding the paper